FIGURE 1. Emergence of synchronization in clapping.
From the following article:
Self-organizing processes: The sound of many hands clapping
Z. Néda, E. Ravasz, Y. Brechet, T. Vicsek and A.-L. Barabási
Nature 403, 849-850(24 February 2000)
doi:10.1038/35002660
a, Global noise intensity (Ig) as a function of
time. The digitized data were squared and the moving average was determined
over a window of size 0.2 s, several times shorter than the clapping period.
A characteristic region indicates the appearance and disappearance of the
synchronized clapping. Over several performances, we recorded 50 similar sequences
of synchronized clapping (for additional data sets and audio recordings, see
http://www.nd.edu/~networks/clap). b, Local noise intensity (
Il), measured by a hidden microphone in the vicinity of a spectator.
c, Order parameter, r, defined as the maximum of the normalized
correlation between the signal c(t) and a harmonic function,
r = [max(t,
)
t+T
t-Tc(t) sin(2
/
T+
)dt]/[t+T
t-Tc(t)dt
], where and T span all possible values. d,
Average noise intensity, obtained by taking a moving average over a 3-s window
of the global noise intensity shown in a. e, The clapping period,
T, defined as the intervals between the clearly distinguishable maxima.
f, The normalized histogram of clapping frequencies measured for 73 high-school
students (isolated from each other) for mode I (black) and mode II (red) clapping.
g, Normalized histogram for mode I and II clapping obtained for a single
student, sampled 100 times over a one-week period.